1. Field of the Invention
This invention generally relates to systems to secure tissue, more particularly to tissue securement systems for treatment of obstructive sleep apnea.
2. Related Art
Obstructive sleep apnea (OSA) is caused by a blockage of the airway, which usually occurs when the soft tissue in the throat collapses and closes during sleep. According to the National Institutes of Health, OSA affects more than twelve million Americans. During each apnea event, the brain briefly arouses the sufferer in order to initiate the resumption of breathing. This type of sleep, however, is extremely fragmented and of poor quality. When left untreated, OSA may result in high blood pressure, cardiovascular disease, weight gain, impotency, headaches, memory problems, job impairment, and motor vehicle crashes. Despite the seriousness of OSA, a general lack of awareness among the public and healthcare professionals results in the vast majority of OSA sufferers remaining undiagnosed and untreated.
In the human body, an air filled space between the nasal cavity and the larynx is referred to as the upper airway. The most critical part of the upper airway associated with sleep disorders is the pharynx. The pharynx has three different anatomical levels. The nasopharynx is the upper portion of the pharynx located in the back of the nasal cavity. The oropharynx is the intermediate portion of the pharynx containing the soft palate, the epiglottis, and the curve at the back of the tongue. The hypopharynx is the lower portion of the pharynx located below the soft tissue of the oropharynx. The oropharynx is the section of the pharynx that is most likely to collapse due to the high prevalence of soft tissue structure, which leaves less space for airflow. The hypopharynx lies below the aperture of the larynx and behind the larynx, and extends to the esophagus.
As is well known to those skilled in the art, the soft palate and the tongue are both flexible structures. The soft palate provides a barrier between the nasal cavity and the mouth. In many instances, the soft palate is longer than necessary and it extends a significant distance between the back of the tongue and the posterior pharyngeal wall.
Although the muscles relax throughout the body during sleep, most of the muscles of the respiratory system remain active. During inhalation, the diaphragm contracts and causes negative pressure to draw air into the nasal cavity and the mouth. The air then flows past the pharynx, through the trachea and into the lungs. The negative pressure causes the tissue of the upper airway to deform slightly, which narrows the airway passage. In apneic patients, the soft palate, the tongue, and/or the epiglottis collapse against the posterior pharyngeal wall to block airflow into the trachea. As the airway narrows, airflow through the pharynx becomes turbulent which causes the soft palate to vibrate, generating a sound commonly known as snoring.
During sleep, humans typically experience brief obstructions of airflow and/or small decreases in the amount of airflow into the trachea and lungs. An obstruction of airflow for more than ten seconds is referred to as apnea. A decrease in airflow by more than fifty percent is referred to as hypopnea. The severity of sleep disorders is measured by the number of apneas and hypopneas that occur during every hour of sleep.
If apnea or hypopnea occurs more than five times per hour, most medical personnel diagnose the individual as having an upper airway resistance problem. Many of these patients often exhibit symptoms related to sleep disorders including sleepiness during the day, depression, and difficulty concentrating.
Individuals having ten or more episodes of apnea or hypopnea during every hour of sleep are officially classified as having obstructive sleep apnea syndrome. As the airway is obstructed, the individual makes repeated attempts to force inhalation. Many of these episodes are silent and are characterized by movements of the abdomen and chest wall as the individual strains to draw air into the lungs. Typically, episodes of apnea may last a minute or more. During this time, oxygen levels in the blood will decrease. Ultimately, the obstruction may be overcome by the individual generating a loud snore or awakening with a choking feeling.
When an individual is awake, the back of the tongue and the soft palate maintain their shape and tone due to their respective internal muscles. As a result, the airway through the pharynx remains open and unobstructed. During sleep, however, the muscle tone decreases and the posterior surface of the tongue and the soft palate become more flexible and distensible. Without normal muscle tone to keep their shape and to keep them in place either alone or as a group, the posterior surface of the tongue, the epiglottis, and the soft palate tend to easily collapse to block the airway.
U.S. Pat. No. 7,367,340 describes one approach to treat sleep apnea and is directed to the use of an element that is anchored to the mandible and is capable of applying force within the tongue to prevent the tongue from collapsing during sleep. In the embodiments described, the device consists of an element that is attached to the mandible though drilling of the mandible to provide a rigid point of fixation. The method of attachment risks damaging the dental anatomy and nerve structures within the mandible.
A commercial implant system, sold under the trademark REPOSE™ by InfluENT of Concord, N.H., uses a titanium screw that is inserted into the posterior aspect of the mandible at the floor of the mouth. A loop of suture is passed through the tongue base and attached to the mandibular bone screw. The REPOSE™ procedure achieves a suspension or hammock of the tongue base making it less likely for the base of the tongue to prolapse during sleep. Due to the high activity of the tongue during wakefulness, however, the suture component of this device may act as a cutting element within the tongue, causing device trans-location and ultimately a loss of efficacy of the procedure thereby requiring subsequent removal. Additionally, the fiber is placed within the tongue through the combination of a sterile and non-sterile approach. An incision is made within the sub-mental space to provide access to the infra-mandibular region to place the screw. Once the screw is attached to the mandible, the fiber element is passed into the tongue through the sub-mental musculature, through the genioglossus and exits out of the mucosal surface of the tongue into the contaminated oral cavity. This passage is accomplished through the use of a linear designed suture passer that grasps the fiber, through the use of a jaw like element, and forces it through the tongue in a straight path. Upon exiting in the oral cavity, the fiber is then passed laterally in a sub mucosal pass through the original puncture formed by the curved suture passer which is essentially an eyed needle.
The use of the eyed needle results in the folding of the fiber in half about the eyelet of the needle, thereby increasing, in an irregular fashion, the projected diameter/dissecting cross section of the device. This increase in projected dissection surfaces results in the creation of a larger hole than is necessary for the single strand of fiber that is to be deposited within the tissue tract.
Furthermore, the use of the jawed type linear suture passer also results in an increased projected cross sectional dissecting surface. The fiber is laid into the jaw and is clamped. In the best case scenario, the jaw resultant projected dissecting tissue surface consists of the cross sectional area of the fiber lying alongside the cross sectional area of the shaft of the linear suture passer.
Another commercially available tongue suspension device, developed by ASPIRE Medical, is named the ADVANCE System. It's similar to the REPOSE suture suspension system for the tongue base in that it utilizes a bone screw in the mandible, but has the advantage of being adjustable. The device utilizes a flexible shape memory anchor within the tongue that is shaped similar to a grappling hook to engage the tissue within the tongue base. It's placed through a small incision in the sub-mental region and the suture is attached to a spool-like component attached to the mandible. Two to four weeks after healing, a small incision is made under the chin and a screw is turned to tighten the suture, thus pulling the device forward. While the device provides a simplified installation technique from within the sterile space, the anchors may suffer from a high rate of device fracture and failure due to loading within the tongue musculature. Additionally, the risk of damage to the teeth or the nerve roots for the teeth is similar to the RESPOSE bone screw.
In spite of the above advances in tongue suspension devices, there remains a need for a tongue suspension method and suture passer device that enables the passage of fiber with minimal increase in the size of the dissected tunnel formed in the traverse of the fiber.